<script>
  let bg = document.getElementById('page-bg');
  bg.style.setProperty('will-change', 'filter', '');
  let hue = 0;
  setInterval(
    function () {
      hue = (hue + 1) % 360.;
      // For dark mode, append: invert(1) saturate(2)
      bg.style.setProperty('filter', 'hue-rotate(' + hue + 'deg)', '');
    }, (5000 / 360.));
</script>
